Monatomic fissure gas diffusion electrode for in-situ production of H2O2 and preparation method of monatomic fissure gas diffusion electrode

Abstract

The invention discloses a monatomic crack gas diffusion electrode for in-situ production of H2O2 and a preparation method, a monatomic metal / NC catalyst is prepared firstly, then the prepared monatomic metal / NC catalyst is doped into the gas diffusion electrode, and the prepared electrode is good in stability, outstanding in durability and convenient to store and transport. The preparation process is simple, raw materials are cheaper than a noble metal catalyst, H2O2 can be efficiently prepared when the catalyst is used for an electrocatalytic reduction reaction, the H2O2 selectivity in the oxidation-reduction two-electron process is improved by about 90% compared with a monomer, the stability is very good, the yield is very prominent, and the method is suitable for industrial production. The method has strong practical significance in wastewater, antibiotic degradation, medical disinfection and even energy storage.

Description

Technical Field

[0001] The present invention relates to the technical field of gas diffusion electrodes, and in particular to a single-atom crack gas diffusion electrode for in-situ H2O2 production and a preparation method thereof. Background Art

[0002] Hydrogen peroxide (H2O2) is a zero-emission, highly efficient chemical oxidant widely used in industrial water treatment. Currently, more than 95% of commercial H2O2 is produced industrially through the anthraquinone process. Although the anthraquinone process is technologically mature and has a well-developed infrastructure, it still has significant disadvantages, such as high operating costs, dangerous explosion problems, and transportation limitations. In recent years, the two-electron redox reaction [ORR, O2 + 2H + +2e - →H2O2] H2O2 production has been shown to be a cost-effective alternative to traditional chemical methods, avoiding the need to transport, store and handle concentrated H2O2.

[0003] Since precious metal alloys can make the selectivity of H2O2 production reach 90%, precious metal catalysts are usually used as cathode catalytic materials for hydrogen peroxide production. However, precious metal alloys are expensive and some materials are toxic, which is not conducive to large-scale application. Carbon-based materials have become a research hotspot due to their advantages such as low cost, good stability, and easy large-scale production. For example, patent CN114144258A discloses a catalyst for generating hydrogen peroxide and its preparation method. However, the active sites of carbon-based catalysts are mainly concentrated in the micropores on the surface of the catalyst, so the density of its active sites is relatively low, resulting in low catalytic activity. The mass transfer and charge transfer efficiency of carbon-based catalysts are relatively low, which limits their performance in applications such as fuel cells. Summary of the Invention

[0004] The present invention aims to overcome the above-mentioned problems existing in the cathode materials for producing hydrogen peroxide in the prior art, and provides a single-atom crack gas diffusion electrode for in-situ production of H2O2 and a preparation method. The prepared metal single-atom catalyst is doped into the gas diffusion electrode. The preparation process is simple, the raw materials are cheaper than precious metal catalysts, and H2O2 can be efficiently produced by electrocatalytic reduction reaction. The prepared crack electrode has good stability, outstanding durability, and is easy to store and transport.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: A method for preparing a single-atom crack gas diffusion electrode for in-situ H2O2 production comprises the following steps: (1) dissolving thiourea in deionized water to obtain a thiourea solution; (2) adding a soluble metal salt to the thiourea solution, stirring the reaction, and then drying, calcining, and grinding the product to obtain a single-atom metal catalyst; the soluble metal salt is selected from one or more of copper salts, nickel salts, and cobalt salts; (3) Soaking the conductive substrate in the PTFE suspension and then taking it out to dry; (4) Mix carbon black and anhydrous ethanol evenly, then add PTFE suspension and single-atom metal catalyst dropwise, and stir vigorously until wet paste to obtain a coating; (5) The obtained coating material is coated on the surface of the dried conductive substrate obtained in step (3), and calcined at 330-370° C. to obtain the single-atom crack gas diffusion electrode.

[0006] The present invention first prepares a single-atom metal / NC catalyst through steps (1) and (2), and then dopes the prepared single-atom metal / NC catalyst into a gas diffusion electrode. Since carbon materials exhibit extremely high chemical inertness in acidic or alkaline electrolytes, compared with metal-based catalysts (such as Pt and Fe), the carbon substrate is not easily oxidized or corroded, thus avoiding the performance degradation caused by material degradation. Moreover, the carbon substrate regulates the oxygen reduction pathway through surface functional groups (such as carbonyl and pyridinic nitrogen), giving priority to the 2eO2 that generates H2O2. - Reaction, rather than 4e to produce H2O - The carbon material has a moderate adsorption strength for the reaction intermediates (such as •OOH), which avoids the catalyst deactivation caused by strong adsorption, and inhibits the accumulation of impurity ions (such as Cl - ) poisoning of active sites. Simultaneously, the present invention doped the catalyst with a single-atom metal / NC catalyst. First, the doping of the single-atom metal / NC catalyst can precisely control the electronic structure of the active site: the single atoms form a coordination structure with the carbon substrate, and through the interaction between the metal d orbitals and the O2 molecules, the adsorption strength of •OOH is optimized, bringing it closer to the ideal value for 2e-ORR (~4.2 eV). Second, the doping of the single-atom metal / NC catalyst can suppress the four-electron pathway: by reducing the propensity for O-O bond breakage (e.g., by avoiding continuous active sites of metal clusters or particles), the generation of H2O is reduced. Furthermore, the metal atoms in the single-atom catalyst are dispersed in an isolated form on the carbon substrate surface, exposing 100% atomic utilization, which can significantly increase the density of effective active sites. The high conductivity of the carbon substrate (which promotes electron transport) combined with the high catalytic activity of the single-atom sites can accelerate the adsorption, activation, and reduction of O2. The synergistic effect of the porous structure of the carbon-based electrode (such as carbon nanotubes and graphene) and the single-atom sites can also enhance O2 diffusion and interfacial reaction efficiency. Therefore, the present invention dopes the single-atom metal / NC catalyst into the catalyst to further increase the hydrogen peroxide yield and enhance the degradation rate.

[0007] Therefore, the electrode prepared by the present invention has good stability, outstanding durability, and is easy to store and transport. The preparation process is simple, the raw materials are cheaper than precious metal catalysts, and the present invention can be used in electrocatalytic reduction reactions to efficiently produce H2O2. The H2O2 selectivity of the two-electron redox process is increased by nearly 90% compared to the monomer, and it has excellent stability and high yield. It has great practical significance in wastewater treatment, antibiotic degradation, medical disinfection, and even energy storage.

[0008] Preferably, the mass volume ratio of thiourea to water in step (1) is 10 g:20-40 mL.

[0009] Preferably, the molar ratio of the metal ion in the soluble metal salt added in step (2) to thiourea is 0.04-0.06.

[0010] Preferably, in step (2), the stirring reaction time is 2-4 hours; the drying temperature is 60-80°C, and the drying time is 2-4 hours; the calcination temperature is 600-700°C, and the calcination time is 3-5 hours.

[0011] Preferably, the solid content of the PTFE suspension in step (3) is 60% to 70 wt%, and the immersion time is 25 to 35 min.

[0012] Preferably, the conductive substrate in step (3) is one of carbon paper, carbon fiber paper, carbon cloth, carbon fiber cloth, and graphite felt.

[0013] Preferably, in step (4), the mass ratio of carbon black to single-atom metal catalyst is 25-75:1; the mass ratio of carbon black to PTFE is 5:2-4.

[0014] Preferably, the stirring temperature in step (4) is 65-75°C.

[0015] Preferably, the loading amount of carbon black on the conductive substrate in step (5) is 10-40 mg / cm 2 .

[0016] Preferably, the calcination time in step (5) is 150-200 min.

[0017] The present invention also provides a single-atom crack gas diffusion electrode for in-situ H2O2 production, which is prepared by the above preparation method.

[0018] Therefore, the present invention has the following beneficial effects: (1) The prepared single-atom metal / NC catalyst is doped into a gas diffusion electrode. The prepared electrode can be used for electrocatalytic reduction reaction to efficiently produce H2O2. The H2O2 selectivity of the two-electron redox process is increased by nearly 90% compared with the monomer; (2) The electrodes prepared by the present invention have good stability, outstanding durability, and are easy to store and transport; (3) The preparation process of the present invention is simple, the raw materials are cheaper than precious metal catalysts, and it is suitable for large-scale application. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a physical picture of the single-atom crack gas diffusion electrode prepared in Example 1 of the present invention.

[0020] Figure 2 This is a SEM image of the single-atom crack gas diffusion electrode prepared in Example 1 of the present invention.

[0021] Figure 3 1 is the LSV curve of the single-atom crack gas diffusion electrode prepared in Examples 1 to 4 of the present invention and Comparative Example 1.

[0022] Figure 4 This is a comparison chart of the hydrogen peroxide production efficiency of the single-atom crack gas diffusion electrodes prepared in Example 1, Examples 5-6 and Comparative Example 1 of the present invention.

[0023] Figure 5 This is a comparison chart of the hydrogen peroxide production effects of the single-atom crack gas diffusion electrodes prepared in Example 1, Examples 5-6 and Comparative Example 1 of the present invention after multiple runs.

[0024] Figure 6 This is a comparison chart of the hydrogen peroxide production efficiency of the single-atom crack gas diffusion electrodes prepared in Example 1, Examples 7-8 and Comparative Example 1 of the present invention. DETAILED DESCRIPTION

[0025] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0026] In the present invention, unless otherwise specified, all equipment and raw materials can be purchased from the market or are commonly used in the industry. The methods in the following embodiments, unless otherwise specified, are all conventional methods in the art.

[0027] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with specific implementation methods. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention rather than limiting the claims of the present invention.

[0028] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0029] Secondly, the term "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in various places throughout this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive of other embodiments.

[0030] Overall embodiment: A method for preparing a single-atom crack gas diffusion electrode for in-situ H2O2 production comprises the following steps: (1) dissolving thiourea in deionized water to obtain a thiourea solution; (2) adding a soluble metal salt to the thiourea solution, stirring the reaction, and then drying, calcining, and grinding the product to obtain a single-atom metal catalyst; the soluble metal salt is selected from one or more of copper salts, nickel salts, and cobalt salts; (3) Soaking the conductive substrate in the PTFE suspension and then taking it out to dry; (4) Mix carbon black and anhydrous ethanol evenly, then add PTFE suspension and single-atom metal catalyst dropwise, and stir vigorously until wet paste to obtain a coating; (5) The obtained coating material is coated on the surface of the dried conductive substrate obtained in step (3), and calcined at 330-370° C. to obtain the single-atom crack gas diffusion electrode.

[0031] As a specific embodiment, the mass volume ratio of thiourea to water in step (1) is 10g:20~40mL.

[0032] As a specific embodiment, the molar ratio of the metal ion in the soluble metal salt added in step (2) to thiourea is 0.04-0.06.

[0033] As a specific implementation method, the stirring reaction time in step (2) is 2 to 4 hours; the drying temperature is 60 to 80° C., and the drying time is 2 to 4 hours.

[0034] As a specific embodiment, in step (2), the calcination temperature is 600-700°C, the calcination time is 3-5 hours, the calcination atmosphere is air, and the heating rate during calcination is 1-10°C / min.

[0035] As a specific implementation, the solid content of the PTFE suspension in step (3) is 60-70 wt %, and the immersion time is 25-35 min.

[0036] As a specific embodiment, the conductive substrate in step (3) is one of carbon paper (CP), carbon fiber paper (CFP), carbon cloth, carbon fiber cloth, and graphite felt (GF).

[0037] As a specific embodiment, in step (4), the mass ratio of carbon black to single-atom metal catalyst is 25-75:1; the mass ratio of carbon black to PTFE is 5:2-4.

[0038] As a specific embodiment, the stirring temperature in step (4) is 65~75°C.

[0039] As a specific embodiment, the loading amount of carbon black on the conductive substrate in step (5) is 10~40mg / cm 2 .

[0040] As a specific embodiment, the calcination time in step (5) is 150 to 200 minutes.

[0041] Example 1: A method for preparing a single-atom crack gas diffusion electrode for in-situ H2O2 production, comprising the following steps: (1) Dissolve 10 g of thiourea in 30 mL of deionized water and form a clear and transparent thiourea solution by ultrasonic treatment; (2) Slowly add 0.918 g of CuCl2·2H2O to the thiourea solution, stir magnetically for 3 h, collect the white crystals by centrifugation, and dry in an oven at 70°C for 3 h; (3) The white crystals were heated to 650°C in air at a rate of 5°C / min and maintained at this temperature for 4 hours. The calcined product was manually ground into powder to obtain the single-atom metal catalyst Cu-NC. (4) The GF was ultrasonically cleaned in acetone and deionized water to remove impurities, and then the cleaned GF was immersed in PTFE suspension (solid content 70 wt%) for 30 min. Finally, the GF was taken out and dried at room temperature; (5) 2.56 g of carbon black was mixed with 40 mL of anhydrous ethanol and ultrasonically shaken. Then, 1.78 g of PTFE suspension (solid content 70 wt%) and 0.05 g of single-atom metal catalyst Cu-NC were added dropwise and vigorously stirred at 70 °C until a wet paste was formed to obtain a coating material; (6) The obtained coating material was coated on one side of the GF obtained in step (4), and calcined at 350°C for 180 min to obtain a carbon black loading of 31.36 mg / cm 2 Single-atom crack gas diffusion electrode.

[0042] The actual picture of the obtained single-atom crack gas diffusion electrode is as follows Figure 1 As shown in Figure 1 It can be seen from the figure that the single-atom crack gas diffusion electrode prepared by the present invention is a layered structure with cracks.

[0043] The SEM image of the obtained single-atom crack gas diffusion electrode is shown in Figure 2 As shown in Figure 2 It can be seen from the figure that the single-atom crack gas diffusion electrode prepared by the present invention has a dense layered structure except for the cracks.

[0044] Example 2: A method for preparing a single-atom crack gas diffusion electrode for in-situ H2O2 production, comprising the following steps: (1) Dissolve 10 g of thiourea in 30 mL of deionized water and form a clear and transparent thiourea solution by ultrasonic treatment; (2) Slowly add 0.895 g of CuCl2·2H2O to the thiourea solution, stir magnetically for 3 h, collect the white crystals by centrifugation, and dry in an oven at 70°C for 3 h; (3) The white crystals were heated to 650°C in air at a rate of 5°C / min and maintained at this temperature for 4 hours. The calcined product was manually ground into powder to obtain the single-atom metal catalyst Cu-NC. (4) The GF was ultrasonically cleaned in acetone and deionized water to remove impurities, and then the cleaned GF was immersed in PTFE suspension (solid content 60 wt%) for 30 min. Finally, the GF was taken out and dried at room temperature; (5) 2.41 g of carbon black was mixed with 40 mL of anhydrous ethanol and ultrasonically shaken. Then, 1.66 g of PTFE suspension (solid content 60 wt%) and 0.05 g of single-atom metal catalyst Cu-NC were added dropwise and vigorously stirred at 70 °C until a wet paste was formed to obtain a coating material. (6) The obtained coating material was coated on one side of the GF obtained in step (4), and calcined at 350°C for 180 min to obtain a carbon black loading of 22.54 mg / cm 2 Single-atom crack gas diffusion electrode.

[0045] Example 3: A method for preparing a single-atom crack gas diffusion electrode for in-situ H2O2 production, comprising the following steps: (1) Dissolve 10 g of thiourea in 30 mL of deionized water and form a clear and transparent thiourea solution by ultrasonic treatment; (2) Slowly add 0.933 g of CuCl2·2H2O to the thiourea solution, stir magnetically for 3 h, collect the white crystals by centrifugation, and dry in an oven at 70°C for 3 h; (3) The white crystals were heated to 650°C in air at a rate of 5°C / min and maintained at this temperature for 4 hours. The calcined product was manually ground into powder to obtain the single-atom metal catalyst Cu-NC. (4) The GF was ultrasonically cleaned in acetone and deionized water to remove impurities, and then the cleaned GF was immersed in PTFE suspension (solid content 70 wt%) for 30 min. Finally, the GF was taken out and dried at room temperature; (5) 2.67 g of carbon black was mixed with 40 mL of anhydrous ethanol and ultrasonically shaken. Then, 1.85 g of PTFE suspension (solid content 70 wt%) and 0.05 g of single-atom metal catalyst Cu-NC were added dropwise and vigorously stirred at 70 °C until a wet paste was formed to obtain a coating material. (6) The obtained coating material was coated on one side of the GF obtained in step (4), and calcined at 350°C for 180 min to obtain a carbon black loading of 44.68 mg / cm 2 Single-atom crack gas diffusion electrode.

[0046] Example 4: A method for preparing a single-atom crack gas diffusion electrode for in-situ H2O2 production, comprising the following steps: (1) Dissolve 10 g of thiourea in 30 mL of deionized water and form a clear and transparent thiourea solution by ultrasonic treatment; (2) Slowly add 0.866 g of CuCl2·2H2O to the thiourea solution, stir magnetically for 3 h, collect the white crystals by centrifugation, and dry in an oven at 70 °C for 3 h; (3) The white crystals were heated to 650°C in air at a rate of 5°C / min and maintained at this temperature for 4 hours. The calcined product was manually ground into powder to obtain the single-atom metal catalyst Cu-NC. (4) The GF was ultrasonically cleaned in acetone and deionized water to remove impurities, and then the cleaned GF was immersed in PTFE suspension (solid content 70 wt%) for 30 min. Finally, the GF was taken out and dried at room temperature; (5) 2.15 g of carbon black was mixed with 40 mL of anhydrous ethanol and ultrasonically shaken. Then, 1.57 g of PTFE suspension (solid content 70 wt%) and 0.05 g of single-atom metal catalyst Cu-NC were added dropwise and vigorously stirred at 70 °C until a wet paste was formed to obtain a coating material; (6) The obtained coating material was coated on one side of the GF obtained in step (4), and calcined at 350°C for 180 min to obtain a carbon black loading of 11.25 mg / cm 2 Single-atom crack gas diffusion electrode.

[0047] Example 5: A method for preparing a single-atom crack gas diffusion electrode for in-situ H2O2 production, comprising the following steps: (1) Dissolve 10 g of thiourea in 30 mL of deionized water and form a clear and transparent thiourea solution by ultrasonic treatment; (2) Slowly add 0.907 g of CuCl2·2H2O to the thiourea solution, stir magnetically for 3 h, collect the white crystals by centrifugation, and dry in an oven at 70°C for 3 h; (3) The white crystals were heated to 650°C in air at a rate of 5°C / min and maintained at this temperature for 4 hours. The calcined product was manually ground into powder to obtain the single-atom metal catalyst Cu-NC. (4) The GF was ultrasonically cleaned in acetone and deionized water to remove impurities, and then the cleaned GF was immersed in PTFE suspension (solid content 70 wt%) for 30 min. Finally, the GF was taken out and dried at room temperature; (5) 2.47 g of carbon black was mixed with 40 mL of anhydrous ethanol and ultrasonically shaken. Then, 1.70 g of PTFE suspension (solid content 70 wt%) and 0.05 g of single-atom metal catalyst Cu-NC were added dropwise and vigorously stirred at 70 °C until a wet paste was formed to obtain a coating material; (6) The obtained coating material was coated on one side of the GF obtained in step (4), and calcined at 350°C for 180 min to obtain a carbon black loading of 24.54 mg / cm 2 Single-atom crack gas diffusion electrode.

[0048] Example 6: A method for preparing a single-atom crack gas diffusion electrode for in-situ H2O2 production, comprising the following steps: (1) Dissolve 10 g of thiourea in 30 mL of deionized water and form a clear and transparent thiourea solution by ultrasonic treatment; (2) Slowly add 0.921 g of CuCl2·2H2O to the thiourea solution, stir magnetically for 3 h, collect the white crystals by centrifugation, and dry in an oven at 70°C for 3 h; (3) The white crystals were heated to 650°C in air at a rate of 5°C / min and maintained at this temperature for 4 hours. The calcined product was manually ground into powder to obtain the single-atom metal catalyst Cu-NC. (4) The GF was ultrasonically cleaned in acetone and deionized water to remove impurities, and then the cleaned GF was immersed in PTFE suspension (solid content 70 wt%) for 30 min. Finally, the GF was taken out and dried at room temperature; (5) 2.62 g of carbon black was mixed with 40 mL of anhydrous ethanol and ultrasonically shaken. Then, 1.73 g of PTFE suspension (solid content 70 wt%) and 0.05 g of single-atom metal catalyst Cu-NC were added dropwise and vigorously stirred at 70 °C until a wet paste was formed to obtain a coating material; (6) The obtained coating material was applied to one side of the GF obtained in step (4) to obtain a carbon black loading of 40.28 mg / cm after calcination at 350°C for 180 min. 2 Single-atom crack gas diffusion electrode.

[0049] Example 7: A method for preparing a single-atom crack gas diffusion electrode for in-situ H2O2 production, comprising the following steps: (1) Dissolve 10 g of thiourea in 30 mL of deionized water and form a clear and transparent thiourea solution by ultrasonic treatment; (2) Slowly add 1.28 g of CoCl2·6H2O to the thiourea solution, stir magnetically for 3 h, collect the white crystals by centrifugation, and dry in an oven at 70 °C for 3 h; (3) The white crystals were heated to 650°C in air at a rate of 5°C / min and maintained at this temperature for 4 hours. The calcined product was manually ground into powder to obtain the single-atom metal catalyst Co-NC; (4) The GF was ultrasonically cleaned in acetone and deionized water to remove impurities, and then the cleaned GF was immersed in PTFE suspension (solid content 70 wt%) for 30 min. Finally, the GF was taken out and dried at room temperature; (5) 2.56 g of carbon black was mixed with 40 mL of anhydrous ethanol and ultrasonically shaken. Then, 1.78 g of PTFE suspension (solid content 70 wt%) and 0.05 g of single-atom metal catalyst Co-NC were added dropwise and vigorously stirred at 70 °C until a wet paste was formed to obtain a coating material. (6) The obtained coating material was coated on one side of the GF obtained in step (4), and calcined at 350°C for 180 min to obtain a carbon black loading of 30.62 mg / cm 2 Single-atom crack gas diffusion electrode.

[0050] Example 8: A method for preparing a single-atom crack gas diffusion electrode for in-situ H2O2 production, comprising the following steps: (1) Dissolve 10 g of thiourea in 30 mL of deionized water and form a clear and transparent thiourea solution by ultrasonic treatment; (2) Slowly add 1.28 g of NiCl2·6H2O to the thiourea solution, stir magnetically for 3 h, collect the white crystals by centrifugation, and dry in an oven at 70°C for 3 h; (3) The white crystals were heated to 650°C in air at a rate of 5°C / min and maintained at this temperature for 4 hours. The calcined product was manually ground into powder to obtain the single-atom metal catalyst Ni-NC; (4) The GF was ultrasonically cleaned in acetone and deionized water to remove impurities, and then the cleaned GF was immersed in PTFE suspension (solid content 70 wt%) for 30 min. Finally, the GF was taken out and dried at room temperature; (5) 2.56 g of carbon black was mixed with 40 mL of anhydrous ethanol and ultrasonically shaken. Then, 1.78 g of PTFE suspension (solid content 70 wt%) and 0.05 g of single-atom metal catalyst Ni-NC were added dropwise and vigorously stirred at 70 °C until a wet paste was formed to obtain a coating material; (6) The obtained coating material was coated on one side of the GF obtained in step (4), and calcined at 350°C for 180 min to obtain a carbon black loading of 31.04 mg / cm 2 Single-atom crack gas diffusion electrode.

[0051] Comparative Example 1: A method for preparing a single-atom crack gas diffusion electrode for in-situ H2O2 production, comprising the following steps: (1) The GF was ultrasonically cleaned in acetone and deionized water to remove impurities. The cleaned GF was then immersed in a PTFE suspension (solid content 70 wt%) for 30 min. Finally, the GF was taken out and dried at room temperature. (2) 2.56 g of carbon black was mixed with 40 mL of anhydrous ethanol, and ultrasonically vibrated. Then, 1.78 g of PTFE suspension (solid content 70 wt%) was added dropwise and vigorously stirred at 70 °C until a wet paste was formed to obtain a coating material; (3) The obtained coating material was applied to one side of the GF obtained in step (1) so that the carbon black loading amount was 32.15 mg / cm 2 The single-atom crack gas diffusion electrode was obtained after calcination at 350° C. for 180 min.

[0052] The LSV (Linear Sweep Voltammetry) curves of the single-atom crack gas diffusion electrodes obtained in Examples 1 to 4 and Comparative Example 1 were tested, and the results were as follows: Figure 3 As shown. Figure 3 It can be seen that the current of the single-atom Cu-NC doped C-PTFE / GF electrode in Example 1 is lower than the current of the C-PTFE / GF electrode not doped with single-atom Cu-NC in Comparative Example 1, indicating that under the same voltage, the single-atom Cu-NC doped C-PTFE / GF electrode undergoes more reactions and has a better effect.

[0053] Hydrogen peroxide production experiments were conducted on the monoatomic crack gas diffusion electrodes obtained in Examples 1, 5-8, and Comparative Example 1. The experimental method was as follows: Using a CHI660E electrochemical workstation as the power source, hydrogen peroxide was prepared in a self-oxygenated three-dimensional in situ hydrogen peroxide generation dual cathode (GDE) system. The prepared composite cathode served as the working electrode, while MMO and Hg / HgO served as the working and reference electrodes, respectively. 0.1 M Na₂SO₄ (100 mL) was used as the electrolyte. The electrolyte was circulated at a constant flow rate of 400 mL / min. No oxygen was introduced into the assembled device for in situ hydrogen peroxide production experiments. The hydrogen peroxide content was measured after a period of operation.

[0054] The results of hydrogen peroxide production per hour in Example 1, Examples 5-6 and Comparative Example 1 are as follows: Figure 4 As shown in Figure 4 It can be seen that the single-atom Cu-NC doped C-PTFE / GF electrode in Example 1 and Examples 5-6 has a higher efficiency and better effect in producing hydrogen peroxide than the C-PTFE / GF electrode not doped with single-atom Cu-NC in Comparative Example 1. The schematic diagram of hydrogen peroxide production after multiple runs of Example 1, Examples 5-6 and Comparative Example 1 is shown in FIG. Figure 5 As shown in Figure 5 It can be seen that the single-atom crack gas diffusion electrodes prepared by the method of the present invention in Examples 1 and 5-6 still have good electrode effects after multiple runs, indicating that the electrodes have good durability and can be reused multiple times. Figure 6 As shown in Figure 6 It can be seen that the single-atom Cu-NC doped C-PTFE / GF electrode prepared in Example 1 has higher hydrogen peroxide production efficiency and better effect than the single-atom Co-NC doped C-PTFE / GF electrode prepared in Example 7 and the single-atom Ni-NC doped C-PTFE / GF electrode prepared in Example 8.

[0055] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for preparing a monoatomic crack gas diffusion electrode for in-situ H2O2 production, characterized in that the steps include: (1) dissolving thiourea in deionized water to obtain a thiourea solution; (2) adding a soluble metal salt to the thiourea solution, stirring the reaction, and then drying, calcining, and grinding the product to obtain a single-atom metal catalyst; the soluble metal salt is one or more of a copper salt, a nickel salt, and a cobalt salt; (3) Soaking the conductive substrate in the PTFE suspension and then taking it out to dry; (4) Mix carbon black and anhydrous ethanol evenly, then add PTFE suspension and single-atom metal catalyst dropwise, and stir vigorously until wet paste to obtain a coating; (5) coating the coating material on the surface of the dried conductive substrate obtained in step (3), and calcining the conductive substrate at 330-370° C. to obtain the single-atom crack gas diffusion electrode.

2. The method for preparing a monatomic crack gas diffusion electrode for in-situ H2O2 production according to claim 1, wherein: The mass volume ratio of thiourea to water in step (1) is 10 g:20~40 mL.

3. The method for preparing a monatomic crack gas diffusion electrode for in-situ H2O2 production according to claim 1, wherein: The molar ratio of the metal ion in the soluble metal salt added in step (2) to the thiourea is 0.04-0.

06.

4. The method for preparing a monatomic crack gas diffusion electrode for in-situ H2O2 production according to claim 1 or 3, characterized in that: In step (2), the stirring reaction time is 2 to 4 hours; the drying temperature is 60 to 80° C., and the drying time is 2 to 4 hours; the calcination temperature is 600 to 700° C., and the calcination time is 3 to 5 hours.

5. The method for preparing a monatomic crack gas diffusion electrode for in-situ H2O2 production according to claim 1, wherein: The solid content of the PTFE suspension in step (3) is 60% to 70 wt%, and the immersion time is 25 to 35 min.

6. The method for preparing a monatomic crack gas diffusion electrode for in-situ H2O2 production according to claim 1 or 5, characterized in that: The conductive substrate in step (3) is one of carbon paper, carbon fiber paper, carbon cloth, carbon fiber cloth, and graphite felt.

7. The method for preparing a monatomic crack gas diffusion electrode for in-situ H2O2 production according to claim 1, wherein: In step (4), the mass ratio of carbon black to single-atom metal catalyst is 25-75:1; the mass ratio of carbon black to PTFE is 5:2-4.

8. The method for preparing a monatomic crack gas diffusion electrode for in-situ H2O2 production according to claim 1, wherein: In step (5), the loading amount of carbon black on the conductive substrate is 10~40mg / cm 2 .

9. The method for preparing a monatomic crack gas diffusion electrode for in-situ H2O2 production according to claim 1 or 8, characterized in that: The calcination time in step (5) is 150-200 min.

10. A monatomic crack gas diffusion electrode for in-situ H2O2 production, characterized by: It is prepared using the preparation method according to any one of claims 1 to 9.

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